Keep old "notfound" interface for backward compatibility

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/errors.go

@@ -33,9 +33,10 @@ func ErrorConnectionFailed(host string) error {
 	return errConnectionFailed{host: host}
 }
 
+// Deprecated: use the errdefs.NotFound() interface instead. Kept for backward compatibility
 type notFound interface {
 	error
-	NotFound()
+	NotFound() bool
 }
 
 // IsErrNotFound returns true if the error is a NotFound error, which is returned